As highways increasingly are compelled to traverse residential areas, hospital zones and even industrial areas in which silence is a virtue, a problem arises with respect to the noise generated by the vehicles traveling on such highways. The problem is particularly pronounced as vehicle size increases and vehicle speed increases both for heavy vehicles and light vehicles.
Not only does the sound generated by traveling vehicles rank as an inconvenience to neighbors of such highways, but there is increasing evidence that continuous high noise levels associated with vehicle travel are detrimental to the health of individuals who dwell or work in the vicinity of highways, throughways, heavily traveled streets and avenues, and even carparks where both engine starting and wheel noise may be significant.
Consequently, proposals have been made to limit the transmission of sound (usually noise) from a vehicle area, e.g. a highway, to adjoining areas involving sound barriers which can be placed along the edges of the street or highway.
It is a common practice to flank the traveling lanes or shoulders of highways and streets with wheel-engaging barriers of small height, generally less than the diameter of an ordinary automobile wheel, to serve as a safety guide or the like. Such safety barriers may be in the form of curbs or simple ridges which flank the road or street.
Somewhat higher road barriers have also been proposed as described, for example, in my U.S. Pat. Nos. 3,603,562; 3,704,861 3,784,167; 3,963,218; 3,881,697; 3,966,173 and 4,047,701; and in the documents or references cited or made of record therein.
In these road barriers, guide strips or planks of considerable length and hence significant transverse flexibility, are spaced above the ground and span spaced apart posts and are intended to guide the vehicle back into a travel lane without excessive rebounding or damage to the vehicle.
In the erection of such structures, the fabrication of new highways, the rebuilding of old highways and application of safety devices including vehicle-guide barriers to existing highways, it is desirable to consider all aspects of the problem, namely, the desire to provide effective road barriers and to provide acoustic barriers where required. Naturally, the current technique of providing sound barriers in addition to existing safety barriers is expensive but perhaps more important is the fact that in many cases there is insufficient room for both safety barriers and acoustic barriers so that a sound-blocking solution frequently results in an unsatisfactory safety level and vice versa. An alternative, of course, is to increase the width of the highway, frequently at prohibitive cost, and the right of way associated therewith.